new 'convert_pasted_images_quality' site setting

app/controllers/uploads_controller.rb

@@ -73,7 +73,7 @@ class UploadsController < ApplicationController
       # convert pasted images to HQ jpegs
       if filename == "blob.png" && SiteSetting.convert_pasted_images_to_hq_jpg
         jpeg_path = "#{File.dirname(tempfile.path)}/blob.jpg"
-        `convert #{tempfile.path} -quality 95 #{jpeg_path}`
+        `convert #{tempfile.path} -quality #{SiteSetting.convert_pasted_images_quality} #{jpeg_path}`
         # only change the format of the image when JPG is at least 5% smaller
         if File.size(jpeg_path) < File.size(tempfile.path) * 0.95
           filename = "blob.jpg"